Method and apparatus for detecting synchronization signal in wireless communication system

ABSTRACT

An operation method of an electronic device including: dividing a cell search period into a plurality of partial detection ranges based on the number of partial buffers and a size of the partial buffer; obtaining a first correlation detection information based on a first synchronization signal, while temporarily storing first signals in a first partial buffer among the partial buffers, in which the first signals are received during a first partial detection range among the plurality of partial detection ranges; and obtaining a second correlation detection information for the first signals based on the first correlation detection information and a second synchronization signal, during a second partial detection range among the plurality of partial detection ranges and obtaining the first correlation detection information for second signals based on the first synchronization signal, while temporarily storing the second signals received during the second partial detection range in a second partial buffer.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.10-2019-0167145, filed on Dec. 13, 2019, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND

Example embodiments of the inventive concepts relate to a wirelesscommunication system. For example, at least some example embodiments,relate to a method and/or an apparatus for detecting a synchronizationsignal in a wireless communication system supporting sidelinkcommunication.

In the wireless communication system, a synchronization signal may beused for cell search or synchronization of user equipment (UE). In thewireless communication system such as long term evolution (LTE) or 5G,the UE may search a cell formed by a base station (BS) by detecting asynchronization signal to be broadcasted from the base station.

Recently, with the development of internet of things (IoT), a sidelinkcommunication system including device to device (D2D) or vehicle toeverything (V2X) communication has been attracting attention. In thesidelink communication system for D2D or V2X, the synchronization signalmay be transmitted at different periods from the LTE or 5G communicationsystem, and may include a primary sidelink synchronization signal (PSSS)and a secondary sidelink synchronization signal (SSSS).

SUMMARY

Example embodiments of the inventive concepts relate to a cell searchmethod of an electronic device, a method of performing cell search byperforming primary sidelink synchronization signal (PSSS) detection andsecondary sidelink synchronization signal (SSSS) detection in parallel,and/or an apparatus performing the same.

According to an example embodiment of the inventive concepts, a methodof operating an electronic device includes dividing a cell search periodinto a plurality of partial detection ranges based on a number ofpartial buffers included in the electronic device and a size of thepartial buffers; obtaining, based on a first synchronization signal,first correlation detection information for first signals receivedduring a first partial detection range among the plurality of partialdetection ranges, while temporarily storing the first signals in a firstpartial buffer among the partial buffers; obtaining, based on the firstcorrelation detection information for the first signals and a secondsynchronization signal, second correlation detection information for thefirst signals, during a second partial detection range among theplurality of partial detection ranges; and obtaining, based on the firstsynchronization signal, the first correlation detection information forsecond signals received during the second partial detection range, whiletemporarily storing the second signals in a second partial buffer amongthe partial buffers.

According to another example embodiment of the inventive concepts, thereis provided an electronic device including a memory including aplurality of partial buffers; and processing circuitry configured to,divide a cell search period into a plurality of partial detection rangesbased on a size of the plurality of partial buffers, obtain, based on afirst synchronization signal, first correlation detection informationfor first signals received during a first partial detection range amongthe plurality of partial detection ranges, while temporarily storing thefirst signals in a first partial buffer among the partial buffers,obtain, based on the first correlation detection information for thefirst signals and a second synchronization signal, second correlationdetection information for the first signals, during a second partialdetection range among the plurality of partial detection ranges, andobtain, based on the first synchronization signal, the first correlationdetection information for second signals received during the secondpartial detection range, while temporarily storing the second signals ina second partial buffer among the partial buffers.

According to another example embodiment of the inventive concepts, thereis provided a modem device including an input buffer including a firstbuffer and a second buffer, the input buffer configured alternatelystore signals corresponding to a partial detection range in a respectiveone the first buffer and the second buffer; and processing circuitryconfigured as a primary sidelink synchronization signal (PSSS) detectorto generate PSSS detection information by calculating a PSSS correlationbased on the signals stored in the first buffer or the second buffer, aPSSS result manager to determine candidate paths based on the PSSSdetection information, a secondary sidelink synchronization signal(SSSS) detector to generate SSSS detection information by calculating aSSSS correlation for the candidate paths, and an SSSS result manager tostore the SSSS detection information.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the inventive concepts will be more clearlyunderstood from the following detailed description taken in conjunctionwith the accompanying drawings in which:

FIG. 1 shows a wireless communication system according to exampleembodiments of the inventive concepts;

FIGS. 2A and 2B show examples of synchronization signals in a sidelinksystem according to example embodiments of the inventive concepts;

FIG. 3 is a block diagram of an electronic device according to exampleembodiments of the inventive concepts;

FIG. 4A shows an operation sequence for performing cell search;

FIG. 4B shows a time flow according to cell search;

FIG. 5 is a block diagram of a modem according to example embodiments ofthe inventive concepts;

FIG. 6 is a flow chart for performing cell search according to anexample embodiment of the inventive concepts;

FIG. 7 shows an operation sequence of a PSSS manager according to anexample embodiment of the inventive concepts;

FIG. 8 shows an operation sequence of a SSSS manager according to anexample embodiment of the inventive concepts;

FIG. 9 shows a time flow of cell search according to an exampleembodiment of the inventive concepts; and

FIG. 10 is another block diagram showing an electronic device accordingto an example embodiment of the inventive concepts.

DETAILED DESCRIPTION

Hereinafter, various example embodiments of the inventive concepts willbe described in detail with reference to the accompanying drawings.

FIG. 1 shows a wireless communication system according to exampleembodiments of the inventive concepts.

Referring to FIG. 1, a plurality of devices (100, 110, 120) and a basestation 200 are disclosed. The plurality of devices 100, 110, and 120and the base station 200 may be illustrated as nodes using a wirelesschannel in the wireless communication system. Hereinafter, forconvenience of description, an electronic device will be described basedon the device 100, and the remaining electronic devices 110 and 120 maybe respectively referred to as a first external device 110 and a secondexternal device 120.

According to various example embodiments, the base station 200 may be anetwork infrastructure that may provide wireless access to the firstexternal device 110. The base station 200 may have coverage 210 to bedefined as a constant geographic area based on distance capable oftransmitting a signal. The base station 200 may be connected to one ormore ‘transmission/reception point (TRP)’. The base station 200 maytransmit a downlink signal to the first external device 110 arrangedinside the coverage 210, or receive an uplink signal therefrom, throughone or more TRPs.

According to various example embodiments, the base station 200 may bereplaced by other terms including an ‘access point (AP)’, an ‘e node B(eNodeB, eNB)’, a ‘5th generation node (5G node)’, a ‘wireless point’,or other terms with equivalent technical meaning, in addition to thebase station.

According to various example embodiments, the electronic device 100, asa device used by user, may be replaced by other terms including an ‘userequipment (UE)’, a ‘mobile station’, a ‘subscriber station’, a ‘customerpremises equipment (CPE)’, a ‘remote terminal’, a ‘wireless terminal’,an ‘user device’, or other terms with equivalent technical meaning, inaddition to a terminal.

According to various example embodiments, the electronic device 100 maycommunicate with the first external device 110 and/or the secondexternal device 120. For example, the communication may correspond todevice to device (D2D) communication. For another example, when theelectronic device 100 is embedded in a vehicle, the communication maycorrespond to vehicle to everything (V2X). When the electronic device100 communicates with the first external device 110 and/or the secondexternal device 120, the first external device 110 and the secondexternal device 120 may arranged inside the coverage of the electronicdevice 100.

Referring to FIG. 1, the first external device 110 may perform D2Dcommunication with the electronic device 100 in a state in whichconnection to the base station 200 is established, and the secondexternal device 120 may perform D2D communication with the electronicdevice 100 even when there is no wireless connection to other devices.The first external device 110 may be referred to as an in-coverageterminal, and the second external device 120 may be referred to as anout-coverage terminal.

According to various example embodiments, the first external device 110may receive synchronization signals from the base station 200. Thesynchronization signals may include a primary synchronization signal(PSS) and a secondary synchronization signal (SSS). The PSS and the SSSmay correspond to a synchronization signal transmitted from the basestation 200 to a terminal (e.g., the first external device 110) insidethe coverage 210.

According to various example embodiments, the electronic device 100 mayreceive sidelink synchronization signals from the first external device110 or the second external device 120. The sidelink synchronizationsignals may refer to the synchronization signals for a sidelinkcommunication system. The sidelink synchronization signals may include aprimary sidelink synchronization signal (PSSS) and a secondary sidelinksynchronization signal (SSSS). That is, since the electronic device 100is not directly connected to the base station 200, D2D communication orV2X communication may be performed with peripheral terminals (e.g., thefirst external device 110 or the second external device 120).Hereinafter, PSSS and SSSS will be described with reference to FIG. 2.

FIGS. 2A and 2B show examples of a sidelink synchronization signal.

FIG. 2A shows resource mapping of PSSS and SSSS in a normal cyclicprefix (CP), and FIG. 2B shows resource mapping of PSSS and SSSS in anextended CP. CP may refer to a guard interval to be inserted between asymbol and a symbol in order to reduce inter-symbol interference.

Referring to FIG. 2A, one subframe to be transmitted based on the normalCP may include 14 symbols. PSSS of the sidelink synchronization signalsmay be assigned to symbols 1 and 2. SSSS of the sidelink synchronizationsignals may be assigned to symbols 11 and 12.

Referring to FIG. 2B, one subframe to be transmitted based on theextended CP may include 12 symbols. In the case of the extended CP, alength of one CP of the extended CP may be longer than that of thenormal CP. PSSS of the sidelink synchronization signals may be allocatedto symbols 0 and 1. SSSS of the sidelink synchronization signals may beallocated to symbols 9 and 10.

FIG. 3 is a block diagram of an electronic device according to exampleembodiments of the inventive concepts.

Referring to FIG. 3, the electronic device 100 may include an antenna310, an RF (radio frequency) circuit 320, a modem 330, a processor 340,a memory 350, and a system interconnect 360.

According to various example embodiments, each of components included inthe electronic device 100 may be a hardware block including an analogcircuit and/or a digital circuit, and may be implemented by a processorexecuting software including a plurality of instructions that transformthe processor into a special purpose processor to perform the functionsof the components.

The RF circuit 320 may receive a wireless signal to be transmitted bythe base station 200 through the antenna 310. For example, the RFcircuit 320 may move the wireless signal that is in a frequency band ofhigh center frequency, to a base band and output it to the modem 330. Inother words, the RF circuit 320 may demodulate the received wirelesssignal to be enabled signal processing in the modem 330, the processor340, or the memory 350. In addition, the RF circuit 320 may receive dataor the like from the modem 330, modulate them, and transmit them to thebase station 200 through the antenna 310.

The processor 340 may include an intelligent hardware device such as acentral processing unit (CPU), a micro-controller, an applicationprocessor, or a graphics processing unit (GPU).

For example, the processor 340 may be implemented in processingcircuitry such as hardware including logic circuits; a hardware/softwarecombination such as a processor executing software; or a combinationthereof and memory. For example, the processing circuitry morespecifically may include, but is not limited to, a central processingunit (CPU), an arithmetic logic unit (ALU), a digital signal processor,a microcomputer, a field programmable gate array (FPGA), a programmablelogic unit, a microprocessor, application-specific integrated circuit(ASIC), etc. The processing circuitry may be special purpose processingcircuitry that may reduce the cell search time by performing SSSSdetection for the first partial detection range in parallel with PSSSdetection for the second partial detection range and may reduce systemload by avoiding redundant calculations on candidate paths throughbypassing SSSS detection for candidate paths where an indicatorindicates that the SSSS correlation result value already exists.

The memory 350 may store software code that is computer readable and/orcomputer executable and includes a plurality of instructions. Accordingto an example embodiment, the memory 350 may store a plurality of signalprocessing algorithms for signal processing of wireless communication.

The memory 350 may include, for example, a volatile memory device suchas dynamic random access memory (DRAM) or synchronous dynamic randomaccess memory (SDRAM). In addition, the memory 350 may include, forexample, a non-volatile memory device such as electrically erasableprogrammable read-only memory (EEPROM), flash memory, phase changerandom access memory (PRAM), resistance random access memory (RRAM),nano floating gate memory (NFGM), polymer random access memory (PoRAM),magnetic random access memory (MRAM), or ferroelectric random accessmemory (FRAM).

The system interconnect 360 may be implemented as a bus to which aprotocol having a predetermined standard bus specification is applied.For example, as the standard bus specification, an advancedmicrocontroller bus architecture (AMBA) protocol from ARM (Advanced RISCMachine) may be applied. The bus types of the AMBA protocol may includeadvanced high-performance bus (AHB), advanced peripheral bus (APB),advanced eXtensible interface (AXI), AXI4, and AXI coherency extensions(ACE), and the like.

FIG. 4A shows an operation sequence for performing cell search, and FIG.4B shows a time flow according to the cell search.

Referring to FIG. 4A, in operation S410, the electronic device 100 maystart the cell search. During the cell search, the electronic device 100may detect a signal broadcast from any device inside the coverage of theelectronic device 100.

In operation S420, the electronic device 100 may detect PSSS during anentire detection range. According to various example embodiments, alength of the entire detection range may be various. For example, in thecase of the electronic device 100 performing D2D communication among thesidelink communication systems, the length of the entire detection rangemay correspond to 40 ms. For another example, when the electronic device100 performs V2X communication, the length of the entire detection rangemay correspond to 160 ms. That is, the electronic device 100 may receivethe signal broadcast from external devices (for example, the firstexternal device 110 or the second external device 120 in FIG. 1)arranged around the electronic device 100 for 40 ms or 160 ms. Referringto FIG. 4B, the entire detection range may correspond to a PSSSdetection range (t_(P)).

In operation S430, the electronic device 100 may select candidate pathsfor SSSS detection based on PSSS detection result. For example, theelectronic device 100 may receive signals during the entire detectionrange, calculate correlation values between respective ones of thereceived signals and the PSSS signal, and identify time positions withrespect to top N signals having the high correlation value by, forexample, sorting the correlation values in descending order. Each of theidentified N signals may correspond to the candidate path. Here, thecandidate path may refer to signals for which SSSS is determined to behighly likely to be detected. For example, referring to FIG. 4B, theelectronic device 100 may calculate the correlation values between thePSSS signal and signals received during the PSSS detection range, andmay select signals corresponding to the top four largest correlationvalues. The time positions for the four candidate paths may correspondto times t=a, t=b, t=c, and t=d, respectively.

In operation S440, the electronic device 100 may perform SSSS detectionfor candidate paths during the entire detection range of a next period.For example, the electronic device 100 may perform the calculation ofthe correlation value 168 times for each of secondary identification(SID) at a time corresponding to time t=a when SSSS may be expected toexist, that is, at time t=a+t_(P) among the entire detection range ofthe next period. The remaining times b, c, and d may be described in thesame way.

Time to be required for SSSS detection, that is, SSSS detection range(t_(S)) may be determined based on the time positions of the identifiedcandidate paths. Here, since the candidate paths to be identified andthe time positions corresponding to the identified candidate paths arealso variable, the lengths of the SSSS detection range and the celldetection range may be variable. Here, the cell detection range (t_(CS))may refer to a period in which PSSS and SSSS detections are completed,and may be understood as a sum of time lengths of PSSS detection range(t_(P)) and SSSS detection range (t_(S)).

For example, referring to FIG. 4B, when candidate paths having a highPSSS correlation value are arranged in front of the entire detectionrange (or PSSS detection range (tP)) (for example, when all candidatepaths are arranged before time t=a), the length of the cell detectionrange (t_(CS)) to be required for PSSS and SSSS detections may be thePSSS detection range (t_(P)) and a first SSSS detection range (t_(S_1)).

For another example, when candidate paths having the high PSSScorrelation value among sidelink synchronization signals of D2Dcommunication are arranged in the back of the entire detection range(for example, when all candidate paths are arranged before time t=d),the cell detection range (t_(CS)) may be the PSSS detection range(t_(P))+a fourth SSSS detection range (t_(S_4)).

Referring to FIG. 4B, for example, when the last time positioncorresponding to one candidate path from among candidate paths is timet=d, it may be confirmed that the length of the fourth SSSS detectionrange (t_(S_4)) is fairly equivalent to the length of the PSSS detectionrange (t_(P)). That is, the length of the cell detection range (t_(CS))may correspond to twice the entire detection range (or PSSS detectionrange (t_(P))). This is because SSSS correlation must be calculated foreach of 168 SIDs with respect to the SSSS to be received at the timethat corresponds to the time positions of the candidate paths in thePSSS detection range (t_(P)) of the next period, by identifying only thetime positions for candidate paths having the high PSSS correlationvalue during the PSSS detection range (t_(P)).

FIG. 5 is a block diagram of a modem according to example embodiments ofthe inventive concepts.

FIGS. 3 and 5, the modem 330 may include an analog to digital converter(ADC) 510, a filter 520 and a cell searcher 530.

For example, the modem 330 or the processor 340 may include processingcircuitry such as hardware including logic circuits; a hardware/softwarecombination such as a processor executing software; or a combinationthereof and memory. For example, the processing circuitry morespecifically may include, but is not limited to, a central processingunit (CPU), an arithmetic logic unit (ALU), a digital signal processor,a microcomputer, a field programmable gate array (FPGA), a programmablelogic unit, a microprocessor, application-specific integrated circuit(ASIC), etc. The processing circuitry may be special purpose processingcircuitry that performs the functions of the analog to digital converter(ADC) 510, the filter 520 and the cell searcher 530, and thesub-components thereof.

According to various example embodiments, the ADC 510 may digitallyconvert the received wireless signal, and the filter 520 may filtersignal corresponding to the frequency band of the synchronization signalfrom the digitally converted wireless signal.

According to various example embodiments, the cell searcher 530 mayinclude an input buffer 531, a PSSS detector 532, a PSSS result manager533, an SSSS detector 534, and an SSSS result manager 535.

For example, the special purpose processing circuitry of the model 330may be configured to perform the functions of the input buffer 531, thePSSS detector 532, the PSSS result manager 533, the SSSS detector 534,and the SSSS result manager 535 such that the processing circuitryreduces the cell search time by performing SSSS detection for the firstpartial detection range in parallel with PSSS detection for the secondpartial detection range and may reduce system load by avoiding redundantcalculations on candidate paths through bypassing SSSS detection forcandidate paths where an indicator indicates that the SSSS correlationresult value already exists.

The input buffer 531 may temporarily store data for the wirelesssignals. The input buffer 531 according to various example embodimentsof the inventive concepts may include at least two or more buffers. Forexample, referring to FIG. 5, the input buffer 531 may include a firstpartial buffer 531_1 and a second partial buffer 531_2. The firstpartial buffer 531_1 and the second partial buffer 531_2 may be referredto as an odd buffer and an even buffer, respectively. In FIG. 5, theinput buffer 531 is illustrated as including two buffers, but is notlimited thereto. According to various example embodiments, the inputbuffer 531 may include three or more buffers.

According to various example embodiments, the first partial buffer 531_1and the second partial buffer 531_2 may alternately temporarily storesignals with respect to the partial detection range. For example, whenthe entire detection range is divided into N partial detection ranges,the first partial buffer 531_1 or the odd buffer may temporarily storesignals to be received during odd-numbered partial detection rangesamong the N partial detection ranges. The second partial buffer 531_2 orthe even buffer may temporarily store signals to be received duringeven-numbered partial detection ranges among the N partial detectionranges.

The input buffer 531 may process PSSS detection and SSSS detection inparallel by alternately receiving signals through at least two or morebuffers. A detailed description thereof will be described later withreference to FIGS. 6 to 9.

FIG. 6 is a flow chart for performing cell search according to anexample embodiment of the inventive concepts.

Referring to FIG. 6, in operation S610, the cell searcher 530 may startthe cell search. The description of operation S610 is redundant withoperation S410 of FIG. 4A and will be omitted.

In operation S620, the cell searcher 530 may set a partial detectionrange. Setting the partial detection range may refer to dividing theentire detection range into a plurality of ranges.

According to various example embodiments, the length of the partialdetection range may be determined based on buffer size of the inputbuffer 531 and type of communication system.

According to an example embodiment, the buffer size of the input buffer531 may be proportional to the length of the partial detection range.For example, when the buffer size of the input buffer 531 is largeenough to store all signals to be received during the entire detectionrange, the electronic device 100 may bypass the dividing into thepartial detection range. For another example, when the buffer size ofthe input buffer 531 is small, the electronic device 100 may divide theentire detection range into a plurality of partial detection ranges, andalternately receive and store signals by using at least two or morebuffers.

In operation S630, the PSSS detector 532 may perform PSSS detection withrespect to the partial detection range. Here, the PSSS detection mayrefer to calculating the correlation value between the received signaland the PSSS signal. According to various example embodiments, the PSSSdetector 532 may be referred to as a first correlation detector. Asdescribed above, assuming that the entire detection range is dividedinto four partial detection ranges, signals received during the firstpartial detection range may be stored in the first partial buffer 531_1.The PSSS detector 532 may perform PSSS correlation calculation in realtime on signals to be sequentially stored in the first partial buffer531_1 during the first partial detection range. That is, signalsreceived during the first partial detection range may be stored in thefirst partial buffer 531_1 and at the same time, may be processed bycorrelation calculation with the PSSS signal. The PSSS detector 532 maytransmit the obtained PSSS correlation calculation value to the PSSSresult manager 533.

In operation S640, the PSSS result manager 533 may perform alignment onthe PSSS correlation result values and select candidate paths. The PSSSresult manager 533 may also be referred to as a first correlation resultmanager. The candidate paths may be signals having a large PSSScorrelation result value and may refer to signals having highprobability of detecting SSSS. The PSSS result manager 533 may receivethe PSSS correlation result values for signals received during the firstpartial detection range in real time, and may sort the correlationresult values in real time in descending order. In addition, the PSSSresult manager 533 may store only a desired (or, alternatively, apredefined) number of the PSSS correlation result values having arelatively a high value while receiving in real time the PSSScorrelation result values for signals received during the first partialdetection range. For example, when the PSSS correlation result value tobe received in real time is smaller than a desired (or, alternatively, apredefined) number of PSSS correlation result values, the PSSS resultmanager 533 may drop the newly received PSSS correlation result value.The PSSS result manager 533 may update the desired (or, alternatively,the predefined) number of result values as candidate paths according tohigh value order among the plurality of the PSSS correlation resultvalues. The predefined number may be expressed as N_PSSS_TOT. Forexample, the PSSS result manager 533 may determine the N_PSSS_TOTsignals among the PSSS result values for signals to be received duringthe partial detection range as the candidate path.

In operation S650, the SSSS detector 534 may perform SSSS detection withrespect to candidate paths. Here, SSSS detection may refer to performingcorrelation calculation for each of 168 SIDs with respect to each of thecandidate paths (for example, a signal having a high PSSS correlationresult value). The SSSS detector 534 may also be referred to as a secondcorrelation detector. Referring to operation S640, the PSSS resultmanager 533 may transmit information on the N_PSSS_TOT candidate pathsto the SSSS result manager 535 and the SSSS detector 534. The SSSSdetector 534 may calculate a plurality of SSSS correlation result valuesbased on 168 SIDs for each of the N_PSSS_TOT PSSSs.

In operation S660, the SSSS result manager 535 may perform alignment onthe SSSS correlation result values. The SSSS result manager 535 may alsobe referred to as a second correlation result manager. The SSSS detector534 may perform calculation for N_PSSS_TOT*168 SSSS correlation resultvalues and may sort them in descending order according to the order ofhighest SSSS correlation result values. The SSSS result manager 535 mayupdate a predefined number of result values among the plurality of SSSScorrelation result values.

In operation S670, the cell searcher 530 may determine whether a nextpartial detection range exists. When the next partial detection rangeexists, PSSS and SSSS detections for the corresponding range may beperformed, and when the next partial detection range does not exist, itmay be determined that PSSS and SSSS detections with respect to theentire detection range are completed. According to an exampleembodiment, the cell searcher 530 may further include a timer (notshown). The timer (not shown) may count during the period of the entiredetection range (or PS SS detection range) according to the type ofsidelink communication system. The timer (not shown) may generate acontrol signal instructing to stop the cell search of the cell searcher530 when the entire detection range has elapsed. Thereafter, in someexample embodiments, the device 100 may synchronize with the device 110using the results of the cell search, for example, the PSSS and SSSSsignals.

FIG. 7 shows an operation sequence of a PSSS manager according to anexample embodiment of the inventive concepts.

FIG. 7 is a detailed embodiment of the operation sequence of the PSSSresult manager 533 that performs sorting on the PSSS correlation resultvalues of FIG. 6 and performs operation S640 for selecting candidatepaths.

Referring to FIG. 7, in operation 710, the PSSS result manager 533 mayclassify PSSS correlation result values with respect to the Mth partialdetection range according to physical identification (PID) value. ThePID value may correspond to a value for indicating either thein-coverage or the out-coverage of the external device that hastransmitted the signal. For example, since the first external device 110of FIG. 1 is connected to the base station 200, the first externaldevice 110 may be an in-coverage external device, and the PID value ofthe signal transmitted by the first external device 110 may be 0. Foranother example, since the second external device 120 of FIG. 1 is notconnected to the base station 200, the second external device 120 may bean out-coverage external device, and the PID value of the signaltransmitted by the second external device 120 may be 1. The PSSS resultmanager 533 may distinguish the PSSS correlation result values into agroup of PID=1 and a group of PID=0.

In operation S720, the PSSS result manager 533 may sort the PSSScorrelation result values in descending order according to the size ofthe PSSS correlation result values in each of the groups with PID=0 andPID=1. The number of PSSS correlation result values sorted in descendingorder may be a desired (or, alternatively, a predefined) number. If thedescending order according to the PID value is shown, it may be as shownin Table 1 below.

TABLE 1 PSSS correlation value Remark PSSS #1_28 0.81 PID = 0 PSSS #1_20.78 PID = 0 PSSS #2_5 0.71 PID = 0 PSSS #3_41 0.69 PID = 0 PSSS #4_980.61 PID = 0 PSSS #2_50 0.58 PID = 0 PSSS #M_13 0.40 PID = 0 PSSS #M_930.35 PID = 0 PSSS #M_4 0.33 PID = 0 PSSS #M_2 0.32 PID = 0 . . . PSSS#2_8 0.90 PID = 1 PSSS #2_13 0.87 PID = 1 PSSS #3_48 0.81 PID = 1 PSSS#5_10 0.75 PID = 1 PSSS #1_87 0.70 PID = 1 PSSS #1_30 0.64 PID = 1 PSSS#M_45 0.61 PID = 1 PSSS #M_70 0.53 PID = 1 PSSS #M_1 0.48 PID = 1 PSSS#M_3 0.47 PID = 1 . . .

In PSSS #A_B shown in Table 1, A may be a value indicating whether thePSSS is signal received during an Ath partial detection range, and B maybe a value indicating how many times the PSSS has been received amongsignals received from the Ath partial detection range.

In operation S730, the top K signals having a large PSSS correlationresult value may be selected from each of the group with PID=0 and thegroup with PID=1 as candidate paths, and information with respect to thecandidate paths may be stored in a PSSS result buffer (not shown). Here,K may correspond to ½ of N_PSSS_TOT. Table 2 shows selected candidatepaths.

TABLE 2 PSSS correlation value Remark PSSS #1_28 0.81 PID = 0 PSSS #1_20.78 PID = 0 PSSS #2_5 0.71 PID = 0 PSSS #3_41 0.69 PID = 0 PSSS #4_980.61 PID = 0 PSSS #2_50 0.58 PID = 0 PSSS #M_13 0.40 PID = 0 PSSS #M_930.35 PID = 0 PSSS #M_4 0.33 PID = 0 PSSS #2_8 0.90 PID = 1 PSSS #2_130.87 PID = 1 PSSS #3_48 0.81 PID = 1 PSSS #5_10 0.75 PID = 1 PSSS #1_870.70 PID = 1 PSSS #1_30 0.64 PID = 1 PSSS #M_45 0.61 PID = 1 PSSS #M_700.53 PID = 1 PSSS #M_1 0.48 PID = 1

In operation S740, information on K candidate paths for each PID groupmay be transmitted to the SSSS result manager 535, and new indicatorinformation may be changed. The new indicator information may beinformation for indicating that an arbitrary signal is first included inthe candidate path of each PID group. A detailed description of the newindicator information will be described later in operation S760.

In operation S750, the PSSS result manager 533 may classify the PSSScorrelation result values with respect to (M+1)th partial detectionrange according to PID values. The (M+1)th partial detection range mayrefer to a partial detection range subsequent to the Mth partialdetection range among the entire detection ranges. The description ofclassifying the PSSS correlation values according to the PID values isredundant with operation S710, and will be omitted. Here, referring toFIG. 5, if signals to be received during the Mth partial detection rangeare stored in the first partial buffer 531_1, and signals to be receivedduring the (M+1)th partial detection range may be stored in the secondpartial buffer 531_2.

In operation S760, the PSSS result manager 533, in each of the groupswith PID=0 and PID=1, may sort PSSS correlation result values of Kcandidate paths selected with respect to the Mth partial detection rangeand PSSS correlation result values of (M+1)th partial detection range indescending order together in real time. That is, the PSSS result manager533 may compare together the top K PSSS correlation result values amongthe signals of all partial detection ranges before the (M+1)th partialdetection range and the PSSS correlation result value of signalsreceived during the (M+1)th partial detection range. Accordingly, thePSSS result manager 533 may obtain the same result as the descendingorder of K candidate paths showing high correlation with the PSSS signalamong all signals received from a first partial detection range to anarbitrary partial detection range.

According to an example embodiment, by comparing top K PSSS correlationvalues with respect to the Mth partial detection range to the PSSScorrelation result values with respect to signals received during the(M+1)th partial detection range in real time, signals having top K PSSScorrelation values may be updated as candidate paths.

For example, PSSS correlation result values for signals received duringthe (M+1)th partial detection range may be smaller than top K PSSScorrelation result values for the Mth partial detection range. Since thesignals having the top K PSSS correlation values are not changed,candidate paths may not be updated.

As another example, P PSSS correlation result values among PSSScorrelation result values for signals received during the (M+1)thpartial detection range may be arranged between the top K PSSScorrelation result values with respect to the Mth partial detectionrange. For example, when P signals among the top K signals in the PID=0group are changed may be shown as follows.

TABLE 3 PSSS correlation value Remark PSSS #1_28 0.81 PID = 0 Newindicator = 0 PSSS #1_2 0.78 PID = 0 New indicator = 0 PSSS #2_5 0.71PID = 0 New indicator = 0 PSSS #3_41 0.69 PID = 0 New indicator = 0 PSSS#M + 1_3 0.67 PID = 0 New indicator = 1 PSSS #M + 1_1 0.64 PID = 0 Newindicator = 1 PSSS #4_98 0.61 PID = 0 New indicator = 0 PSSS #2_50 0.58PID = 0 New indicator = 0 PSSS #M + 1_13 0.45 PID = 0 New indicator = 1

Referring to Table 3, it may be seen that PSSS #M+1_3, PSSS #M+1_1, andPSSS #M+1_13 are newly added as candidate paths. Table 3 shows onlysorting in descending order for the group with PID=0, but is not limitedthereto. It may be clearly understood that the group with PID=1 issorted in descending order.

In operation S770, candidate paths having new indicator information of 1may be selected from each of the candidate paths of the group with PID=0and the group with PID=1, and information on the selected candidatepaths may be stored in the PSSS result buffer.

Referring to Table 3, it may be seen that new indicator values of newlyadded PSSS #M+1_3, PSSS #M+1_1, and PSSS #M+1_13 are 1. That is, sincethe three signals have been selected as candidate paths in the previouspartial detection range and have never calculated the SSSS correlationresult value, the new indicator value may be 1. Since information onsignals with a new indicator value of 0 has previously transmitted tothe SSSS result manager 535 and the SSSS detector 534, the PSSS resultmanager 533 may provide information on candidate paths with the newindicator value of 1 to SSSS result manager 535 and SSSS detector 534.

FIG. 8 shows an operation sequence of a SSSS manager according to anexample embodiment of the inventive concepts.

FIG. 8 illustrates an operation sequence of the SSSS detector 534performing operation S650 of performing SSSS detection for the candidatepaths of FIG. 6.

Referring to FIG. 8, in operation S810, the SSSS detector 534 may obtaininformation with respect to candidate paths corresponding to the Mthpartial detection range. Referring to operation S740 of FIG. 7, the SSSSdetector 534 may receive information with respect to K candidate pathsfor each PID group from the PSSS result manager 533.

In operation S820, the SSSS detector 534 may perform SSSS detection withrespect to candidate paths and change new indicator information for thecandidate paths into 0.

According to an example embodiment, when M=1, all candidate pathsreceived by the SSSS detector 534 may have new indicator information of1, and the SSSS correlation value may not exist. In this case, the SSSSdetector 534 may perform SSSS detection for each of the K candidatepaths to obtain the SSSS correlation result value and change the newindicator information into 0. That is, by changing the new indicatorinformation into 0, it may be possible to indicate whether SSSSdetection has been previously performed for each candidate path. TheSSSS detector 534 may transmit the SSSS correlation result value to theSSSS result manager 535.

In operation S830, the SSSS detector 534 may obtain information ofcandidate paths corresponding to the (M+1)th partial detection range.Information of candidate paths corresponding to the (M+1)th partialdetection range may correspond to information received from the PSSSresult manager 533 in operation S770.

According to an example embodiment, candidate paths corresponding to the(M+1)th partial detection range may be the same as candidate pathscorresponding to the Mth partial detection range, and when the signalnewly added to candidate path exists among signals of the (M+1)thpartial detection range, at least some candidate paths corresponding tothe (M+1)th partial detection range may be different from candidatepaths corresponding to the Mth partial detection range.

In operation S840, the SSSS detector 534 may perform SSSS detection onlywith respect to candidate paths for which the new indicator informationis 1, and change new indicator information for candidate paths for whichthe SSSS detection is performed, into 0.

According to an example embodiment, the SSSS detector 534 may notperform SSSS detection for a candidate path where a new indicatorinformation value is 0 because it is included in an existing candidatepath among the top K candidate paths. The SSSS detector 534 may performSSSS detection only for the candidate path where a new indicatorinformation value is 1 because it is newly incorporated into thecandidate paths among the top K candidate paths. That is, by bypassingSSSS detection for candidate paths where the SSSS correlation resultvalue already exists, the number of SSSS detections for the entiredetection range may be reduced while reducing a system load of the cellsearcher 530.

FIG. 9 shows a time flow of cell search according to an exampleembodiment of the inventive concepts. Descriptions overlapping FIGS. 6to 8 will be omitted.

Referring to FIG. 9, signals received during partial detection range #1may be temporarily stored in a first partial buffer 531_1, and at thesame time, the PSSS detector 532 may perform PSSS detection with respectto signals to be received to the first partial buffer 531_1 in realtime. Hereinafter, signals to be received during the partial detectionrange #1 will be referred to as first signals.

The PSSS detector 532 may complete PSSS detection for the partialdetection range #1 and transmit PSSS correlation result values for thefirst signals to the PSSS result manager 533 in real time.

The PSSS result manager 533 may sort the PSSS correlation result valuesto be received from the PSSS detector 532 in descending order in realtime and select any number of candidate paths having a high value inreal time. The PSSS result manager 533 may transmit information ofcandidate paths for the partial detection range #1 to the SSSS detector534 and the SSSS result manager 535 at the end time of the partialdetection range #1.

Signals received during the partial detection range #2 may betemporarily stored in the second partial buffer 531_2, and at the sametime, the PSSS detector 532 may detect PSSS for signals to be receivedto the second partial buffer 531_2 in real time. Hereinafter, signals tobe received during the partial detection range #2 will be referred to assecond signals.

That is, PSSS detection for the second signals may be performed duringthe partial detection range #2, and at the same time, SSSS detection forthe candidate paths selected among the first signals in the partialdetection range #1 may be simultaneously performed in parallel.Descriptions of the partial detection range #3 to the partial detectionrange #M are redundant and will be omitted.

The SSSS result manager 535 may complete the update of the SSSSdetection result only by performing one SSSS detection from the timewhen the entire detection range ends. That is, the time to be requiredfor PSSS and SSSS detections with respect to the entire detection rangemay be greatly reduced at up to twice the total detection range.

Referring to FIGS. 1 to 9, the electronic device according to variousexample embodiments of the inventive concepts are described based onPSSS and SSSS detection, but is not limited thereto. It will be apparentto those skilled in the art that it may be applied to PSS and SSSdetection of LTE communication systems and 5th generation (5G)communication systems according to various example embodiments.

FIG. 10 is another block diagram showing an electronic device accordingto an example embodiment of the inventive concepts.

Referring to FIG. 10, as an example of the electronic device, a wirelesscommunication device 1100 may include an application specific integratedcircuit (ASIC) 1110, an application specific instruction set processor(ASIP) 1130, a memory 1150, a main processor 1170, and a main memory1190. Two or more of the ASIC 1110, ASH′ 1130, and main processor 1170may communicate with each other.

In addition, at least two or more of the ASIC 1110, the ASH′ 1130, thememory 1150, the main processor 1170, and the main memory 1190 may beembedded in one chip.

According to various example embodiments, the ASIP 1130 may be anintegrated circuit customized for a specific use, may support adedicated instruction set for a specific application, and executeinstructions included in the instruction set.

According to various example embodiments, the memory 1150 maycommunicate with the ASH′ 1130 and store a plurality of instructionsexecuted by the ASH′ 1030 as a non-transitory storage device, and thememory 1150 may include any type of memory accessible by the ASIP 1130,such as random access memory (RAM), read only memory (ROM), tape,magnetic disk, optical disk, volatile memory, non-volatile memory, andcombinations thereof.

According to various example embodiments, by executing a series ofinstructions stored in the main memory 1150, the ASIP 1130 and/or themain processor 1170 may detect PSSS and SSSS from the wireless signaland perform cell search based on the detected PSSS and SSSS, asdescribed through FIGS. 1 to 9.

According to various example embodiments, the main processor 1170 maycontrol the wireless communication device 1100 by executing a pluralityof instructions. For example, the main processor 1170 may control theASIC 1110 and the ASIP 1130, process data received through a wirelesscommunication network, or process user input to the wirelesscommunication device 1100. In addition, the main memory 1190 maycommunicate with the main processor 1170 and may store the plurality ofinstructions executed by the main processor 1170 as the non-transitorystorage device.

While the inventive concepts have been particularly shown and describedwith reference to some example embodiments thereof, it will beunderstood that various changes in form and details may be made thereinwithout departing from the spirit and scope of the following claims.

What is claimed is:
 1. A method of operating an electronic device, themethod comprising: dividing a cell search period into a plurality ofpartial detection ranges based on a number of partial buffers includedin the electronic device and a size of the partial buffers; obtaining,based on a first synchronization signal, first correlation detectioninformation for first signals received during a first partial detectionrange among the plurality of partial detection ranges, while temporarilystoring the first signals in a first partial buffer among the partialbuffers; obtaining, based on the first correlation detection informationfor the first signals and a second synchronization signal, secondcorrelation detection information for the first signals, during a secondpartial detection range among the plurality of partial detection ranges;and obtaining, based on the first synchronization signal, the firstcorrelation detection information for second signals received during thesecond partial detection range, while temporarily storing the secondsignals in a second partial buffer among the partial buffers.
 2. Themethod of claim 1, wherein the obtaining of the first correlationdetection information for the first signals further comprises:calculating first correlation values between each of the first signalsstored in the first partial buffer and the first synchronization signal;sorting a set number of the first correlation values in descendingorder; determining the set number of the first signals sorted by thefirst correlation values as candidate paths; and obtaining the secondcorrelation detection information for the first signals based on thecandidate paths.
 3. The method of claim 2, wherein the obtaining of thesecond correlation detection information for the first signals furthercomprises: identifying, among the candidate paths, at least onecandidate path having a new indicator information equal to a firstvalue; and calculating a correlation value between the at least onecandidate path and the second synchronization signal.
 4. The method ofclaim 3, wherein the obtaining of the second correlation detectioninformation for the first signals further comprises: identifying, amongthe candidate paths, a candidate path having the new indicatorinformation equal to a second value, the second value being differentfrom the first value; bypassing, for the identified candidate path, thecalculating of the correlation value between the identified candidatepath and the second synchronization signal; and changing, for the atleast one candidate path, the new indicator information with respect tothe at least one candidate path where the correlation value iscalculated, to the second value.
 5. The method of claim 2, furthercomprising: alternately storing the signals such that the signalsreceived during the first partial detection range are stored in thefirst partial buffer and the signals received during the second partialdetection range are stored in the second partial buffer.
 6. The methodof claim 1, wherein the obtaining the second correlation detectioninformation for the first signals is performed in parallel with theobtaining of the first correlation detection information for the secondsignals.
 7. The method of claim 2, wherein the obtaining of the firstcorrelation detection information for the second signals furthercomprises: sorting, in descending order, the first correlation valuesfor ones of the first signals determined as the candidate paths and thefirst correlation values for the second signals to generate sorted firstcorrelation values; and updating the set number of the first correlationvalues among the sorted first correlation values as the candidate paths.8. The method of claim 2, wherein the sorting in descending orderfurther comprises: classifying the first correlation values according toa primary identification (PID) value into at least a first group and asecond group, the PID value indicating whether an external devicebroadcasting the first synchronization signal and the secondsynchronization signal to the electronic device is connected to a basestation; and separately sorting each of the first group of the firstcorrelation values and the second group of the first correlation valuesaccording to the first correlation values in descending order.
 9. Themethod of claim 1, wherein the first synchronization signal includes aprimary sidelink synchronization signal (PSSS) or a primarysynchronization signal (PSS), and the second synchronization signalincludes a secondary sidelink synchronization signal (SSSS) or asecondary synchronization signal (SSS).
 10. An electronic devicecomprising: a memory including a plurality of partial buffers; andprocessing circuitry configured to, divide a cell search period into aplurality of partial detection ranges based on a size of the pluralityof partial buffers, obtain, based on a first synchronization signal,first correlation detection information for first signals receivedduring a first partial detection range among the plurality of partialdetection ranges, while temporarily storing the first signals in a firstpartial buffer among the partial buffers, obtain, based on the firstcorrelation detection information for the first signals and a secondsynchronization signal, second correlation detection information for thefirst signals, during a second partial detection range among theplurality of partial detection ranges, and obtain, based on the firstsynchronization signal, the first correlation detection information forsecond signals received during the second partial detection range, whiletemporarily storing the second signals in a second partial buffer amongthe partial buffers.
 11. The electronic device of claim 10, wherein theprocessing circuitry is configured to, calculate first correlationvalues for each of the first signals stored in the first partial buffer,sort the first correlation values in descending order, determine a setnumber of signals among the sorted correlation values for the firstsignals as candidate paths, and obtain the second correlation detectioninformation for the first signals based on the candidate paths.
 12. Theelectronic device of claim 11, wherein the processing circuitry isconfigured to, identify, among the candidate paths, at least onecandidate path having a new indicator information is a first value, andcalculate, for the at least one candidate path, a second correlationvalue between the at least one candidate path and the secondsynchronization signal.
 13. The electronic device of claim 12, whereinthe processing circuitry is configured to, identify, among the candidatepaths, a candidate path having the new indicator information equal to asecond value, the second value being different from the first value,bypass, for the identified candidate path, calculating of the secondcorrelation value, and change, for the at least one candidate path, thenew indicator information with respect to the at least one candidatepath where the second correlation value is calculated, to the secondvalue.
 14. The electronic device of claim 11, wherein the first signalsand the second signals are alternately received during the first partialdetection range and the second partial detection range, respectively,and the first partial buffer is configured to store the first signalsreceived during the first partial detection range and the second partialbuffer is configured to store the second signals received during thesecond partial detection range.
 15. The electronic device of claim 10,wherein the processing circuitry is configured to obtain the secondcorrelation detection information for the first signals in parallel withthe first correlation detection information for the second signals. 16.The electronic device of claim 11, wherein the processing circuitry isconfigured to, sort, in descending order, the first correlation valuesfor ones of the first signals determined as the candidate paths and thefirst correlation values for the second signals to generate sorted firstcorrelation values, and update the set number of signals among thesorted first correlation values as the candidate paths.
 17. Theelectronic device of claim 11, wherein the processing circuitry isconfigured to, classify the first correlation values for signalsaccording to a primary identification (PID) value into a first group anda second group, the PID value indicating whether an external devicebroadcasting the first synchronization signal and the secondsynchronization signal to the electronic device is connected to a basestation, and separately storing the first group of the first correlationvalues and the second group of the first correlation values according tothe PID in descending order.
 18. The electronic device of claim 10,wherein the first synchronization signal comprises a primary sidelinksynchronization signal (PSSS) or a primary synchronization signal (PSS),and the second synchronization signal comprises a secondary sidelinksynchronization signal (SSSS) or a secondary synchronization signal(SSS).
 19. A modem device comprising: an input buffer including a firstbuffer and a second buffer, the input buffer configured alternatelystore signals corresponding to a partial detection range in a respectiveone the first buffer and the second buffer; and processing circuitryconfigured as, a primary sidelink synchronization signal (PSSS) detectorto generate PSSS detection information by calculating a PSSS correlationbased on the signals stored in the first buffer or the second buffer, aPSSS result manager to determine candidate paths based on the PSSSdetection information, a secondary sidelink synchronization signal(SSSS) detector to generate SSSS detection information by calculating aSSSS correlation for the candidate paths, and an SSSS result manager tostore the SSSS detection information.
 20. The modem device of claim 19,wherein the processing circuitry is configured such that the SSSSdetector generates the SSSS detection information in parallel with thePSSS detector generating the PSSS detection information.